The present invention relates to a multistation press or a comparable forming machine having a plurality of working stations arranged one behind another in a transport direction and through which workpieces successively pass, tables arranged to be movable out of the working stations and equipped with devices for receiving tools and carrying tooling receiving devices, a transfer device for transporting the workpieces among the working stations, the transfer device having at least two carrying rails extending essentially parallel to the transport direction, cross traverses operatively arranged between the carrying rails and carrying a tooling with holding devices for controlled holding and releasing of the workpieces, at least one driving device configured to move the cross traverses on a defined transfer curve and having height adjusting devices configured to permit vertical adjustment of the cross traverses, and rotary drive devices for controlled rotation of the holding devices about an axis oriented transversely with respect to the transport direction, a control device configured to control at least operation of the height adjusting device and of the rotary drive devices.
In multistation presses or comparable forming machines, particularly transfer presses, the tools must be changeable. The tools include top and bottom tools which are arranged in individual press stations for machining sheet metal parts. While the top tool is held on the press slide, the bottom tool is mounted on a so-called sliding table which can be moved laterally out of the press. For the tool change, the top tool has been deposited on the bottom tool so that the complete tool can be moved out of the multistation or transfer press by means of the sliding table.
In addition to the actual tools, the transfer press has additional workpiece-specific devices. These include parts of the transfer press which have the purpose of further transporting the sheet metal parts from one press station to the next. The transfer system is constructed, for example, as a two-rail transfer. Two carrying rails extend on both sides of the press stations longitudinally through the transfer press. Moving carriages are disposed on the carrying rails, between which moving carriages cross traverses are held. By way of driving cams and corresponding transmitting devices, the carrying rails are subjected to a lifting/lowering movement, and the moving carriages are subjected to a backward and forward movement such that the cross traverses travel through a desired transfer curve.
The cross traverses carry devices for the receiving or holding and the controlled releasing of workpieces. These devices are, for example, vacuum-operated suction devices which are arranged on the ends of corresponding suction arms. These suction device arrangements are also called suction spiders. The arrangement of the suction devices, i.e., the construction of the suction spiders, is tool-specific. The suction spiders are therefore part of the workpiece-specific tooling which must also be changed during the tool exchange.
German Patent 3843975 C1 discloses a transfer device for a transfer press having horizontally and vertically moved carrying rails. Between the carrying rails, cross traverses are held which, by way of actuators provided on the carrying rails, can be swivelled in a limited areas about their transverse axis. The cross traverses carry a workpiece-specific tooling and must be exchanged during the tool change. The tools arranged in the press stations are held on sliding tables which can be moved laterally out of the press. On the sliding tables, so-called alignment pins are held which are constructed vertically adjustably by pressure media, i.e., have an active construction. For the tool change, the alignment pins are adjusted upwards approaching the cross traverses to be accommodated. They receive the cross traverses and are then lowered again. However, hydraulically operated active alignment pins disadvantageously require a pressure medium connection to the sliding table and the alignment pins.
In addition, DE 4208205 A1 describes an arrangement for transfer presses for the exchange of workpiece holders (tooling) which requires only passive tooling depositing devices. For the transfer of the cross traverses from the transfer system to the alignment pins, a transfer unit is provided which can be adjusted in its height and in its longitudinal direction. This transfer unit is formed by a vertical pressure cylinder whose piston rod carries the receiving device for the cross traverses and whose cylinder is adjustably arranged by a parallelogram guide in a force-actuated manner on a circular-arc-shaped path. In addition, swivel movements can be carried out. This transfer unit requires, however, additional installation space and additional constructional expenditures.